SU1700199A1 - Method for insulating water inflow in well - Google Patents

Abstract

The invention relates to an oil producing industry and is intended to isolate the flow of formation water in wells. The purpose of the invention is: increasing the efficiency of the method due to uniformity of tamponing of the treated area and an increase in the duration of action. For this purpose, aqueous solutions of calcium chloride and sulfuric acid salts with an equivalent ratio of gypsum-forming ions are sequentially pumped. Sodium tripolyphosphate (TPN) in an amount of 0.05-0.25% by weight of calcium sulfate forming is preliminarily introduced into the chlorine solution of calcium, and solutions of 6-10% concentration are used as an aqueous solution of a salt of sulfuric acid. The introduction of the ESRD slows down the process of gypsum formation. Thanks to this, a more complete and uniform mixing of the reagents in the treated zone occurs. As soon as the potential amount of the gypsum sediment exceeds the inhibitory effect of the ESRD, an avalanche precipitation occurs over the entire length of the treated zone. Moreover, the density of the sediment, its association with the rock and resistance to erosion are increased. It is recommended to inject equal volumes of reactive solutions into the well, their volumes are determined by the required depth of impact on the formation. The method is recommended for isolating water inflows in highly watered wells with inhomogeneous permeability formations. 2 tabl "(L S H

Description

The invention relates to the oil industry, in particular, to methods for isolating the flow of formation water in oil and gas wells.

The purpose of the invention is to increase the efficiency of the method by uniformly tamping the treated area and increasing the duration of action.

The method involves the sequential injection of aqueous solutions of calcium chloride and sulfuric acid salts with an equivalent

g

 the valence ratio of gypsum-forming ions.

The purpose of the invention is achieved by adding sodium tripaliphosphate to the calcium chloride solution in an amount of 0.05-0.25% by weight of the calcium sulfate formed.

The method uses water-soluble salts of sulfuric acid, which can form a precipitate of gypsum when mixed with calcium chloride solution, for example, sodium sulphate, potassium, etc.

The introduction of sodium tripolyphosphate slows down the process of hypoforming, due to which there is a more complete and uniform mixing of the reacting solutions in the treated zone. As soon as the potential amount of the gypsum sediment, the potential for the inhibitory effect of sodium tripolyphosphate, is exceeded, an avalanche-like sedimentation of the precipitate occurs, which leads to an increased content

1700199

from which high

and lasting isolation effect.

The use of the method with a salt concentration of sulfuric acid of more than 10% is not recommended due to the possibility of premature gypsum formation in pipelines during the injection of reagents, as well as the absence of an increase in the isolation effect. Additive sodium tripolyphosphate less than 0.05%, as can be seen from experiments 1- 3 in the table. 2, does not achieve the objectives of the invention, and the content of more than 0.25% does not give

sediment particles per unit volume of the formation increases the effect and only leads to

and more dense packaging of these particles. The introduction of sodium tripolyphosphate makes it possible to refuse the use of portions of a buffer liquid separating reactive solutions020

In addition, due to the specific interaction of sodium tripolyphosphate with gypsum particles, the tampon sediment has an increased stability.

to erosion by a stream of water and a greater length. Equal objects injection is recommended.

bodyworking effect

To test the effectiveness of the method, a reservoir model is used, which consists of two interconnected cylindrical columns of core holders with 30 lengths of 0.2 m and an internal diameter of 0.05 m filled with natural sandstone. The formation model is saturated with a mixture of an aqueous solution of calcium chloride and sodium tripolis phosphate. Then order- ,,. An aqueous solution of a salt of sulfuric acid is added. The model is left alone during the day. Then, the permeability of the model is determined after 1, 5, and 15 days. The research results are summarized in table. 1 and 2.

As follows from the data table. 1, the proposed method provides an increase in the uniformity of plugging.

Claims (1)

reactive solutions with the appropriate choice of salt concentrations. A positive feature of the method is the lack of use of 1 buffer liquids, which simplifies well treatment. The method is recommended for isolating water inflows in highly watered wells with inhomogeneous permeability formations. Invention Formula A method for isolating the inflow of water into a well, including the sequential injection of aqueous solutions of calcium chloride and sulfuric acid salt, characterized in that, in order to increase the efficiency of the method due to uniform tamponirovanie the treated area and increase the duration and duration compared to the effectiveness of the solution chloris40 with the famous. In the known method, the isolation efficiency decreases sharply with time, a uniform clogging of the formation is not achieved. The lower limit of the concentration of the solution of salt of sulfuric acid, as can be seen from experiments 1-3 in table. 1 is equal to 6%, the excess consumption of sodium tripolyphosphate The method is carried out using standard field technology by preliminarily preparing solutions of calcium chloride with the addition of sodium tripolyphosphate and a salt of sulfuric acid, followed by sequential injection of solutions into the formation In addition, sodium tripolyphosphate in the amount of 0.05-0.25% by weight of calcium sulfate formed is preliminarily added, and solutions of 6-10% concentration in an amount equivalent to the ratio of the gypsum-forming ions are used as the aqueous solution of the sulfuric acid salt. Note. The amount of inhibitor is 0.05% by weight of calcium sulfate precipitated. Table 1 table 2